<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <!-- 数据代理：通过一个对象代理对另一个对象中的属性的操作 -->
  <script type="text/javascript">
    let obj = { x: 100 }
    let obj_ = { y: 200 }
    Object.defineProperty(obj_, 'x', {
      get() {
        return obj.x
      },
      set(value) {
        obj.x = value
      }
    })
  </script>
</body>

</html>